(i) In figure (i) O is the vertex, OA, OB is its arms and name of the angle is ∠AOB or∠BOA or simply ∠O.
(ii) In figure (ii) Q is the vertex, QP and QR its arms and the name of the angle is ∠PQR or ∠RQP or simply ∠Q.
(iii) In figure (iii), M is the vertex, MN and ML and its anus, and the name of the angle is ∠LMN or ∠NML or simply ∠M.